A large-scale antenna array is one of key technologies for improving a throughput of a wireless communications system, and also provides a basis for spatial multiplexing of data streams on more layers.
In an existing Long Term Evolution (LTE) system, a multiple-antenna configuration already supports spatial multiplexing of data streams on up to eight layers. To support simultaneous transmission of data streams on up to eight layers, a maximum of eight antenna ports are configured for pilot signals such as demodulation reference signals (DMRS) in terms of structure. A DMRS of each antenna port is discretely distributed on a time-frequency resource of each resource block (RB) pair. In an existing LTE protocol, resource elements (RE) that are occupied by a DMRS on each RB pair are configured based on a maximum transport layer quantity (that is, 8), and overheads of the REs that are occupied by the DMRS on each RB pair account for 14.3%. Even if only one transport layer is used in actual data stream transmission, a pilot resource that is pre-configured based on the maximum transport layer quantity still needs to be reserved for a time-frequency resource of each layer. Consequently, idle pilot resources are a great waste, resulting in extremely low resource usage.
With development of communications systems, a quantity of transport layers for a data stream certainly increases. If a time-frequency resource is still allocated to a pilot signal by using an existing method, overheads of REs that are occupied by the pilot signal on each RB pair increase as the maximum transport layer quantity increases. For example, when the maximum transport layer quantity is 8, overheads of REs that are occupied by a DMRS on each RB pair account for 14.3%; or when the maximum transport layer quantity is 16, overheads of REs that are occupied by a DMRS on each RB pair account for 28.6%. It may be learned that, when the maximum transport layer quantity is larger, more idle pilot resources are wasted.
Therefore, how to improve usage of idle pilot resources becomes a technical problem urgently to be resolved.